Fixing device

Abstract

A fixing device includes a fixing belt configured to heat a recording material, a pressure member configured to press the fixing belt, and a sliding member configured to be in sliding contact with an inner peripheral surface of the fixing belt and being opposed to the pressure member. The pressure member and the fixing belt form a fixing nip portion, and heat and pressure are applied to the recording material at the fixing nip portion to fix a toner image onto the recording material. The sliding member includes a plurality of protrusions on a surface of the sliding member that is in sliding contact with the inner peripheral surface of the fixing belt. The following expressions are satisfied: The fixing belt satisfies the prescribed formula.

What is claimed is: 
     
       1. A fixing device comprising:
 an endless fixing belt configured to heat a recording material; 
 a pressure member configured to press the fixing belt; and 
 a sliding member configured to be in sliding contact with an inner peripheral surface of the fixing belt and being opposed to the pressure member, 
 wherein the pressure member and the fixing belt form a fixing nip portion, and heat and pressure are applied to the recording material at the fixing nip portion to fix a toner image onto the recording material, 
 wherein the sliding member includes a plurality of protrusions on a surface of the sliding member that is in sliding contact with the inner peripheral surface of the fixing belt, and 
 wherein the following expressions are satisfied:
   1 Pd   2 ≤0.8 [N (Newton)]  (1)
 
   1≤15.6×( Pd   4 )/( Et   3 ) [mm]  (2)
 
 
 where P [MPa] represents a pressure on the fixing nip portion, E [MPa] represents a Young's modulus of the fixing belt, t [mm] represents a thickness of the fixing belt, and d [mm] represents a distance between the plurality of protrusions in a sheet width direction of the recording material. 
 
     
     
       2. The fixing device according to  claim 1 , wherein the sliding member includes a base material portion provided with the plurality of protrusions, and the base material portion and the plurality of protrusions are integrally formed of metal. 
     
     
       3. The fixing device according to  claim 1 , wherein, in the sheet width direction, the distance between the plurality of protrusions corresponds to a distance between ends of adjacent protrusions. 
     
     
       4. The fixing device according to  claim 1 , wherein the sliding member includes a sliding layer and the sliding layer covers at least the plurality of protrusions. 
     
     
       5. The fixing device according to  claim 1 , wherein, in the sheet width direction in the fixing nip portion, a width of an area of the sliding member that is in contact with the fixing belt is smaller than a width of an area of the sliding member that is out of contact with the fixing belt. 
     
     
       6. The fixing device according to  claim 1 , wherein the plurality of protrusions are located at regular intervals in the sheet width direction. 
     
     
       7. The fixing device according to  claim 1 , wherein the distance between the plurality of protrusions is a value calculated by averaging a plurality of distances between the plurality of protrusions. 
     
     
       8. The fixing device according to  claim 1 , wherein the Young's modulus of the fixing belt is set in the following range: 5000-150000 MPa.